Geographic Range

Atelocynus microtis is native to the northern part of South America and has been found in the Amazon basin regions of Brazil, Peru, Ecuador and Colombia. It has also been sighted in the upper Rio Orinoco basin in Colombia and Venezuela and the upper Rio Parana basin in Mato Grosso, Brazil. (Berta, 1986)

Habitat

Atelocynus microtis prefers undisturbed lowland rainforests in the Amazon region. Within these lowland forests, there are records of A. microtis occupying terra firme forest, swamp forest, stands of bamboo and areas of primary succession along rivers, and there have been several reports of small-eared dogs swimming in rivers along with a prevalence of tracks along riverbanks and creeks. Whether or not they are able to use other habitats is still unknown, but there has been one sighting of an individual in a lowland forest that bordered savanna. There are very few records of A. microtis in areas with significant human activity or impact. (Berta, 1986; Leite Pitman and Williams, 2004)

Physical Description

Atelocynus microtis is a mid-sized canid with a large, fox-like head, short ears that are rounded at the tips, relatively short legs, and a long, bushy tail. Small-eared dogs have thick, sleek, dark pelage that may be in shades of brown, black, or gray and gradually fades into a dull reddish-brown on the underside. Markings include a narrow black collar, a dark band that extends along the top of the back and tail, and a patch of light-colored hairs around the pubic region and underside of the base of the tail. Individuals may exhibit different color patterns, but it remains unclear if these variations reflect age, distribution, molt, or other factors.
Possibly because of their propensity to use water sources, small-eared dogs have a partial interdigital membrane. A pair of captive individuals were also described as having a notably visible tapetum lucidum, which caused the eyes to reflect brightly in conditions of low light. Compared to related species of South American foxes, small-eared dogs are fairly large. They have relatively short limbs and small ears compared to similar species and females are slightly larger than males. (Berta, 1986; Leite Pitman and Williams, 2004; Macdonald, 2006)

Reproduction

Little information is known about the mating system of A. microtis and no information has been published on this topic. Females have been found with pups on rare occasions but no information is available regarding how mates are attracted or how their mating system works. (Leite Pitman and Williams, 2004)

General reproductive behavior has not been formally studied in A. microtis, so little is known. Based on the finding of a juvenile carcass, it is believed that small-eared dogs give birth in May or June. Pups have also been found in the months of April, September, November, and December, suggesting that parturition occurs during the dry season. However, when breeding occurs and the length of gestation is unknown. Adults have been found with 2 or 3 pups in dens in hollow logs or paca burrows. Information on weaning or when pups reach sexual maturity is not known. (Leite Pitman and Williams, 2004)

Because studies of parental investment have not been formally conducted in A. microtis, little is known about the extent of the investment made at various stages of development. However, like all mammals, females invest substantially in gestation and lactation and young have been observed with females, suggesting some period of dependency. (Leite Pitman and Williams, 2004)

Parental Investment

pre-fertilization

provisioning

protecting

female

pre-hatching/birth

provisioning

female

protecting

female

pre-weaning/fledging

provisioning

female

Lifespan/Longevity

Nothing is known of the expected lifespan of A. microtis in the wild. In captivity, most short-eared dogs do not survive a full year. However, two captive animals have lived for 9 and 11 years, respectively. (Leite Pitman and Williams, 2004)

Behavior

Much of what is known about A. microtis comes from observations of a few captive specimens. In observations of a captive pair at the Brookfield Zoo in Chicago, IL, it was noted that the male was dominant over the female despite his smaller size. The male also produced secretions from his anal glands when startled or threatened, producing a strong, musky odor. This odor did not seem to be present in the female. When one of the individuals was startled or felt threatened it would growl, bare its teeth, and attempt to bite. A report from a small group of hunters with domestic dogs in Brazil of a mother with pups showing aggression in defending her young and attacking one of the domestic dogs seems to support these observations. Atelocynus microtis has also been observed erecting the hairs on the tip of its tail when it becomes excited, suggesting the common name given to these dogs by the natives of the Rio Tapojoz region of Brazil: “flag-tailed wild dogs."

Multiple sightings of small-eared dogs in and around rivers, coupled with their partial interdigital membrane, have led to the belief that they are at least partially aquatic. There is limited data pertaining to the social structure of small-eared dogs. Aside from a few sightings of pairs of small-eared dogs, the data seems to point toward A. microtis being a largely solitary animal. They are considered diurnal because 95% of the observations of A. microtis during field research were made during the day. However, it is suspected that this is due at least in part to when observers were present, since they have been photographed walking and swimming at night. Small-eared dogs may be active at any time of the day or night. (Berta, 1986; Leite Pitman and Williams, 2004)

Home Range

No information is available on home range size.

Communication and Perception

There is very little data on communication in small-eared dogs. Given their strong odor, the anal gland secretions are likely used as a device for communication. Also, the displays of aggression such as bared teeth and growling are almost certainly used as a warning to ward off potential threats. (Berta, 1986)

Food Habits

An ongoing study at the Cocha Cashu Biological Station using scat samples to better understand the diet of A. microtis has provided a significant amount of information. Small-eared dogs are generalist carnivores, but also appear to eat some fruits as well. The most prevalent item in their diet appears to be fish, which has been supported by the findings of Defler and Santacruz, who discovered the parasite Diphyllobothrium latum, which requires fish as an intermediary host, in the intestine of a museum specimen. Scat samples also contained insects and the remains of mammals such as agoutis, marsupials, and small rodents. About 10% of the samples contained the remains of fruits such as Borismenia japurensis, Strychnos asperula, Unonopsis floribunda, Pouteria procera, Sciadotenia precatoria, Trattinnickia species, and various Cucurbitaceae and Maraceae. In a couple of scat samples, Euterpe precatoria fruit was germinating. While they do not appear to be a major component of the small-eared dog’s diet, remnants of frogs, crabs, reptiles, and vegetable fiber were also found in some samples. There have also been some reports of A. microtis eating fallen Brosimum fruits and bananas as well as killing and eating poultry. Captive individuals in Bogota, Colombia were fed raw meat, kikuyu grass shoots, and foods that humans would typically eat. (Berta, 1986; Leite and Williams, 2008)

Predation

There are no unequivocal data on what animals (if any) prey on A. microtis, but the presence of ocelot tracks around the remains of a juvenile in Cocha Cashu suggest that it may be a predator. Jaguars and pumas may also be predators due to their size and presence in the same habitats as A. microtis. (Leite Pitman and Williams, 2004)

Ecosystem Roles

Little information is known about the general ecology of A. microtis as it is such an elusive species. Because A. microtis has a sleek, thick coat, it is suggested that it inhabits areas near water or with heavy rainfall and its short limbs allow for it to move about easily within dense forests. Small-eared dogs are generalist carnivores, preying on fish, insects, small mammals, amphibians, birds, and reptiles. They are also thought to be seed dispersers, as germinating fruit seeds have been found in their scat. They may be prey to ocelots, jaguars, and pumas.
Small-eared dogs are hosts to various viruses. Common canine distemper virus and canine parvovirus affect this species and are transmitted through domestic and feral dogs. They are hosts to the cestode Diphyllobothrium latum, which requires a fish intermediate host. (Berta, 1986; Leite Pitman and Williams, 2004)

Economic Importance for Humans: Positive

Because small-eared dogs are so elusive, there have been only a few reports of them having positive economic importance for humans. Short-eared dogs are occasionally hunted for meat, although not for fur. They have been captured in some cases for pets and for sale to local people and zoos. These instances, however, are rare. (Leite Pitman and Williams, 2004)

Economic Importance for Humans: Negative

Atelocynus microtis has no negative economic impact on humans directly, although it can carry the diseases canine distemper virus and canine parvovirus, both of which can occur in domestic and feral dogs. It is probably commoner, however, for domestic and feral dogs to transmit diseases to the short-eared dog. (Leite Pitman and Williams, 2004)

Conservation Status

With a population estimated at only 15,000 individuals, short-eared dogs are one of the rarest species of carnivores in South America. They are listed as near threatened according to IUCN’s Red List of Threatened Species. The major threats to this species are habitat loss and transmission of diseases from domestic dogs. These diseases include canine distemper virus and canine parvovirus. There are few reports of short-eared dogs being hunted for meat and no reports of hunting for fur. Short-eared dogs are not listed on any CITES appendix, but they are listed as an endangered species and protected by law in Brazil, and are currently on a preliminary list of endangered species in Colombia. In Peru, the species was recently taken off the list of protected species. Although there are efforts to protect short-eared dogs in some South American countries, no conservation efforts have been made to increase population numbers. Furthermore, at present no known short-eared dogs are being held in captivity, although there have been individuals held in zoos in the past.
There is ongoing research being conducted on short-eared dogs in Peru. Efforts are being made to provide vaccinations for domestic dogs in the range of short-eared dogs in order to prevent disease transmission and there are efforts in place to expand studies of their ecology and conservation outside of Peru. (Leite and Williams, 2008; Leite Pitman and Williams, 2004)

Other Comments

The generic name Atelocynus comes from the Greek words "ateles" (imperfect) and "cyon" (dog) while microtis is formed from the Greek words "micros" (small) and "ot" (ear).

Atelocynus microtis is referred to as "huiwa toto" by the Amarakaeri people of Peru. The term means "solitary devil", and was given to the species due to the belief that it attacks men by biting their testicles. (Berta, 1986; Leite Pitman and Williams, 2004)

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

causes or carries domestic animal disease

either directly causes, or indirectly transmits, a disease to a domestic animal

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal

active during the day, 2. lasting for one day.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

omnivore

an animal that mainly eats all kinds of things, including plants and animals

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

piscivore

an animal that mainly eats fish

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

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The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.

This material is based upon work supported by the
National Science Foundation
Grants DRL 0089283, DRL 0628151, DUE 0633095, DRL 0918590, and DUE 1122742. Additional support has come from the Marisla Foundation, UM College of Literature, Science, and the Arts, Museum of Zoology, and Information and Technology Services.